I would like to recommend the Youtube channel of Isaac Arthur to you. It concerns itself with various aspects of futurism, tackling everything from technological utopias, eco-friendly archologies and transhumanism to interstellar colonization and megastructures.

All videos cover their respective subject in depth and carry lots of information, and they are all extremely fascinating.

Here is the playlist for megastructures (i.e. Dyson Spheres and the like). Please enjoy and have your minds blown: